Adventure at Hogwarts
by JustYourAverageFanfictionUser
Summary: The war with Voldemort is approaching. As Percy Jackson, Leo Valdez, Sadie and Carter Kane venture deeper into Hecate's secret world, dangerous obstacles appear, and their identity is in danger of being revealed.
1. Chapter 1

**Hi guys! This is my first fanfiction on Fanfiction, and it's a crossover between HOO, Kane Chronicles and HP. This mainly happens during the Order of Pheonix and after BoO and the Serpent's Shadow. I will probably constantly switch between POVs, and I apologize if any of the characters are a bit OOC. **

**Disclaimer:**

**I don't own HP, HOO or Kane chronicles. They belong to J.K. Rowling and Rick Riordan.**

Chapter 1: Accepting the invitation to attend Pigpimples

Percy's POV

Great. Just great. What have we just agreed to?

Standing beside Leo was Hecate, the goddess of magic, crossroads and the Mist herself. Her eyes shimmered with amusement at the reluctance we had shown after she had told us about what she needed us for.

Not that we had any choice in the matter of whether we would go or not, of course. We only agreed because we weren't in the mood to be blasted to smithereens by the gods themselves.

Apparently, there was this world that Hecate had created a world where gods of mythology rarely intervened in mortals' business. I envy the people who had the privilege of being ignored by these 'divine' beings. Also, the mortals who lived in the world of Hecate's had the ability to wield wands, which helped them channel magic, or bend the uppermost layer of the Mist to their will.

Hecate had requested that only Leo and I go to this world of hers to help out. The reason? A _war_. I mean like, _seriously_? Another war? Can't the Fates just give us a break and go back to knitting other people's socks of death?

As if that wasn't enough-we weren't the only (half) mythological beings going either.

Sadie's POV

Hullo, Sadie here. You might be wondering why I'm recording another one of these recordings. Well, the answer isn't simple at all. In fact, it's rather complicated.

About half a year ago, my brother, Carter and I had met these people who were demigods-half-human, half Greek god. Yes, Greek mythology is all real. We can all cheer now. Yay! Whoopee! Hurray! [Don't roll your eyes, Carter. It isn't good for you. What do you mean I do it all the time?]

Recently these demigods contacted us by Iris-messaging-yes, that's a thing-and told us that they needed our help. Their goddess of magic, Hecate, had created a world of wizards and witches about several thousand years ago, but now, they're in the middle of a war, so Hecate decided that it was a good idea to send some demigods over to help. I don't think so. [cue thunder and lightning]

Then the demigods thought, _Hey! It'll be a good idea to have someone experienced to help us! Oh, wait! Didn't those Egyptian magicians say they knew magic? Let's ask for their help! Yay!_

So that's why we're here now, at the borders of Camp Half-blood, completely drenched in the heavy rain, waiting for Percy Jackson and Annabeth Chase to come out and let us in.

"Sadie! You're here already?" A distinct blonde figure yelled, cupping her hands to her mouth.

"About time you get here!" I grumbled. "We've been standing in the rain for so long!"

"Right, sorry. We had no idea you'd be so early." Annabeth's boyfriend, Percy, said sheepishly.

"Who's that with you?" My brother asked curiously.

I noticed that there was another person beside Percy and I peered at him, trying to get a closer look through the rain.

The boy looked like those troublemakers who manage to get a joke out of every situation. He was grinning maniacally and Carter took a step back.

"This is Leo-"

"Leo Valdez, supreme commander of the Argo ll, Mr. Mcshizzle and the boy ON FIRE!"

His hair burst into flames, which were immediately put out by the heavy rain. Carter yelped. I shook my head and gave him a silent look of disapproval. "Tsk tsk tsk...be more polite, Carter."

"Alright," Annabeth said, "so you guys will have to travel to 12 Grimmauld Place, which is the headquarters of the Order of Pheonix, the secret organization of wizards working against Voldemort. Then, you'll see the one who you'll probably need to protect-Harry Potter, he has a lightning-shaped scar on his forehead, should be easy to recognize-and attend Hogwarts or whatever school they have there. After that, await instructions via IM. That clear?"

"You said, you guys. You aren't coming." I have to say, sometimes I'm impressed by Carter's observational skills. He still needs some work on more important stuff though-for example, those awful pickup lines he always uses on Zia. [Quit glaring at me, Carter. You know it's true.]

"Unfortunately, Hecate specifically requested for these two to go." She grimaced and gestured to Percy and Leo, "I just hope that they'll be able to come back during the holidays."

"Now that's settled," Leo interrupted, "how do we plan on traveling to the awesome headquarters of the totally great secret organization?"

Carter grinned. Freak chose that specific moment to burst into the vacant space directly above us, not even tired after his trip through the Duat.

"Talk about the right timing and a dramatic entrance," Percy said. His and Leo's jaws had dropped all the way into the Underworld.

I smirked and Annabeth continued giving us information, unfazed by Freak's sudden appearance, "So you'll be traveling in the boat the griffin carries through the Duat. Don't worry, Zeus won't and can't blast you out of the sky since you're technically in the Egyptian version of a more complicated Mist."

We stepped (mostly) gracefully in the boat. "Freeeeeeeak!"

And we were off.

Harry's POV

Harry had just finished yelling at Ron and Hermione for not telling him anything, but he already felt a twinge of guilt working its way into his mind. He shook it out of his head. He _deserved_ to know after all he had done, didn't he?

He heard a series of banging on the door to his bedroom, but he didn't open it.

"Harry, if you don't open the door _this second, _we'll force it open!" Ron yelled.

With a sigh, he undid the lock on the door, and Hermione and Ron charged in. There were tear stains on Hermione's robes, and Harry instantly felt guilty for yelling at his best friends when it clearly wasn't their fault.

"I'm sorry-" Harry started.

"It's fine, mate. Save the apologies for later. Dumbledore just called a meeting, and all of us are allowed to go." Ron said gruffly. Hermione stayed silent, which was most unlike her.

Harry nodded and together, the trio walked into the room where all the Order members were already waiting. Dumbledore himself was sitting at the head of the table.

"Ah, Harry, Ron, Hermione, you have arrived," The professor said in his usual calm tone, "As the unavoidable war with Voldemort-" Here, the majority of the members flinched, Harry not included, "approaches, I thought it appropriate to call in some allies from our friends in America."

Dumbledore continued, this time with a somewhat mischievous glint in his eye as if he knew something they didn't-which, Harry thought, was most likely the case-"They will be transfer students at Hogwarts, and they will be arriving and staying here until the term starts."

A collective gasp rose among the members.

"Are you sure it's safe to reveal our location to complete strangers, Albus?" Sirius asked, unconvinced.

"I have to agree with Sirius on this one, Harry. We don't even know them!" Hermione murmured under her breath.

"I assure you all that they can be trusted. But they also have their own secrets, and it would be unwise if anyone were to not respect their privacy and attempt to reveal them." Dumbledore seemed to glance meaningfully at Harry, Hermione, and Ron, "But other than that, I hope you will welcome them with open arms. After all, they will arrive tomorrow morning at the latest."


	2. Chapter 2

**Thank you for the favorites!**

**Disclaimer: I don't own HP/ PJO/ Kane Chronicles. J.K. Rowling and Rick Riordan do.**

Chapter 2: Crash-landing inside a secret base

Harry's POV

"Harry. Harry! Wake up!"

Harry groaned and rolled over in his bed, ignoring the multiple voices that were urging him to wake up and go down for breakfast.

"HARRY!" Somebody shook him violently by the shoulders. "The American transfer students are coming over today! Do you really want them to have a bad first impression on you?"

Harry opened his eyes blearily and saw Hermione out of the corner of his eye, and Fred and George, who were holding a glass of water each. Realization dawned on him as he realized what the sneaky twins were planning to do to him.

He jumped out of bed, dodging the twins who were complaining loudly about Harry ruining the fun and quickly made way for the bathroom.

Ten minutes later, he emerged from the bathroom, refreshed and ready for a good breakfast. He was also looking forward to meeting the Americans, though he admitted that he had his own suspicions about them: why did Dumbledore trust them so much? Was it really a good idea to let down their guard and invite these strangers here?

Still, they couldn't be _that_ bad-not if Dumbledore trusted them so much. Harry wouldn't blame them if they were arrogant, bossy or ungrateful. After all, they probably only didn't understand how lucky they were to have such normal lives. Harry wondered if they could become possible friends.

He sat down a the table, ready to dig into his food when all of a sudden, a loud '_boom_' interrupted the peaceful household.

Percy's POV

Yay.

We had successfully crash-landed Freak and the boat in the kitchen of our destination-quite possibly scaring all the residents nearby to death by the huge noise we had just made. There was also a woman screeching in the background about something that sounded like, "Filthy buddy traitors!"

Beside me, Leo was cackling like a Disney villain; sometimes I seriously wondered if that guy was born laughing crazily at shocked nurses and doctors.

It would make a whole lot of sense.

Sitting at a table near us was a boy with a startled expression on his face. He looked like me in a way: his black hair was as messy as mine, and his eyes were a shade of emerald green. A scar was visible on his forehead.

Carter groaned, clambering out of the wreckage of the boat. Sadie was fine, but Freak had disappeared back into the Duat. As I mentioned before, Leo was doing the classic Disney villain laugh beside me; he was _more_ than ok.

"Merlin's beard! What just happened?" A redheaded, middle-aged woman rushed down the stairs, took one look at the damage done to the house, turned her eyes on us, and immediately started fussing over us.

"Any injuries? Are all of you fine?"

"We're fine, ma'am," Carter responded politely. Wow. That guy had manners. Sadie looked impressed.

Two men walked towards us; one had a wooden leg and a fake eyeball that whizzed around in the socket, and I had a sneaking suspicion that it could see through pretty much anything; the other had a pale face and semi-long black hair. They looked nothing similar, yet you were able to tell their expressions were the same-they didn't trust us. Not one bit.

"Well, it looks like our guests have arrived."

Sadie's POV

So we were just standing there, the people from this 'Order' thing staring at us. One redheaded boy in particularly goggled at us as if we were aliens.

"Blimey, mate, how did you get in here?"

I scowled at him. Being a polite lady as always, I didn't scowl at everyone immediately when we got here. [What, Carter? It's true. And didn't I tell you not to roll your eyes?]

"That's none of your business."

"You didn't have to be rude." A bushy-haired girl countered.

"He didn't have to stare at us rudely first."

"It wasn't Ron's fault! He didn't mean to!"

"Well-"

"Guys, as much as I love the immediate drama, I-" Leo faltered under the death glares the girl and I were sending him.

Percy coughed, turning the others' attention to him. "Hi. We're the… um…"

"American exchange students from the Olympus School of Life. Our school specializes in combat magic." A-ha, big brother Carter to the rescue. Still, the Olympus School of Life? Real subtle, Carter. Real subtle. I'm starting to think that we wouldn't be able to last a day without being busted. Oh, the joy of living in fear of others finding out your true identity!

[Thank you, Carter. I'm glad you acknowledge my natural drama skills. Admit it, it was a compliment.]

After five minutes of silence (I'm surprised the demigods were able to keep quiet for that long), the woman who saw us arrive first broke the tension.

She smiled kindly and warmly at us. "Come on, dears. Let's get you to your rooms."

As it turned out, I would be sharing a room with Hermione Granger, the girl I argued with earlier, and Ginny Weasley, Mrs. Weasley's only daughter. I sighed and plopped down on the bed with Hermione staring suspiciously at me. Ginny was much friendlier and before we knew it, we were giving each other our self-introductions.

"Hi, I'm Ginny. I have 6 older brothers, and I'm the only girl in my family. I'm a 4th year at Hogwarts."

"I'm Hermione. 5th year at Hogwarts."

"Sadie Kane. A 5th-year transfer student from the Olympus School of Life in America."

"So, Sadie, tell me more about this school of yours." Hermione leaned forward curiously and started firing a bunch of questions at me. "Where exactly is it? Who's your headmaster? Why do you specialize in combat magic? How different is your way of learning from ours?"

"Firstly, I can't tell you the exact location of the school for safety reasons. Secondly, our school has two houses and the heads of houses share the role of headmaster together. Thirdly, it's because we have more enemies in America. Lastly, I haven't been to your school yet, so I can't tell."

Wow, thank you, Carter, for discussing these questions with us during our trip here. I must admit that his smartness sometimes _does_ come in handy. Speaking of Carter, I wonder how the boys are doing?

Percy's POV

So far, so bad. 1 minute into our 'talk' and Harry and Ron are already suspicious of us.

We aren't really talking right now. Leo is just fiddling with his toolbelt and Carter and I are sitting on the bed across Harry and Ron and we're looking at each other awkwardly. No one attempted to start a conversation between us.

Surprisingly it was Ron who spoke to me first. "What's that on your arm?"

Huh? I glanced at my arm he was pointing to. _Oh._ The SPQR tattoo, a reminder of Hera's rather stupid (cue thunder) yet successful idea of sending me to Camp Jupiter. I covered it with my sleeve and didn't reply to his question. They looked suspiciously at my arm.

"So you're the boy who lived?" Leo looked up eagerly from what seemed to be a mini Argo ll model.

"Um… yeah." Harry shifted uncomfortably.

"He protected the philosopher's stone when he was 11, defeated the basilisk when he was 12, successfully cast a Patronus charm when he was 13 and survived You-know-who yet again when he was 14! What have _you_ done? I bet we could defeat You-know-who without your help." Ron fired at us.

"Listen here," I was starting to get annoyed by their distrust towards us. "Just because you've faced your worst enemy a few times, doesn't mean that others have been through less than you. From where we come from, we've been through at least 2 wars. We've been through more than you can imagine." 

Leo nodded vigorously and Carter continued my little 'speech' for me. "We're here to help you guys, and we're n your side. So can you just respect us until this is all over?"

Silence.

"Um, are you coming with us tomorrow to Diagon Ally?"


	3. Chapter 3

**Chapter 3: Going to Diagon Alley… just your average shopping trip**

Harry's POV

Harry sighed, prodding his breakfast with his fork. He had no appetite, but he pretended to be eating out of being polite to Percy, one of the transfer students.

Percy had woke up early that day and volunteered to make breakfast. _The most delicious breakfast you'll ever have eaten, _he had promised. It turned out to be blue pancakes. A large shriek had echoed around the house when Hermione had seen the blue pancakes. She insisted that it wouldn't be healthy to consume so much food coloring. Still, it was the only food available in the house.

30 minutes later everybody was ready to go. They lined up in front of the fireplace which Mrs. Weasley threw some Floo powder into.

"Um… Harry? You sure that it's safe to walk into green flames?" Carter eyed the fireplace nervously.

Ron snorted. "Of course it's safe. Have you never traveled by Floo network before in America?"

"Ron!" Mrs. Weasley admonished. "They said they had a lot of enemies in America. Perhaps it's too easy to track down people who travel by Floo?" She looked at them for confirmation.

Percy quickly nodded. "Exactly," Sadie said, beaming.

"I don't think so, Harry," Hermione whispered in Harry's ear, casting a suspicious look at the transfer students. "How else would they be able to travel? They don't have broomsticks; they're too young to Apparate, and we don't even know how they got here in the first place.'

_Of course, _Harry thought. _Hermione's the smart one. It makes sense. _

He made a silent vow to keep an eye on the transfer students at all times.

Percy's POV

"Diagon Alley," I said loudly and clearly. A few seconds passed and I found myself clambering out of the fireplace at our destination.

Leo had already arrived, and the others quickly popped out of the fireplace a few minutes later.

"Well," Mrs. Weasley started, "Now we're all here, let's go get your school supplies, shall we?"

Leo cheered and ran down the alley, occasionally stopping by shops he found that he deemed worth looking at. Carter and Sadie followed closely, making small comments such as, "How do these sticks work?" or "They fly on broomsticks?".

I tagged along to the trio of Harry, Hermione, and Ron and followed them into what seemed to be a magical pet store. I winced as all the owls sent me hostile looks and screeched loudly at the idea of having a son of Poseidon being near them.

"They don't like you," Harry observed.

Cue my extremely intelligent answer for emergency situations: "Um, _yeah_."

It's not like I could say to them in their faces: _yo, guys, I'm a demigod. The owls hate me because of this rivalry between my dad, Poseidon, and Athena that's been going on for a few millennia now. Cool, right?_

Then, we split up, and I walked faster to catch up with Hermione, who was studying the display cabinet at some shop. We walked in to find shelves of books all for the purpose of studying magic. Cool, but I don't read.

I collected all the books on my booklist and walked over to a corner Hermione was studying intensely.

"Um… hi," I said awkwardly.

"Rubbish." She was muttering to herself. "Look, Percy! These _ways_ of Divination… they don't make sense! How is this supposed to work!?"

"I have a friend back home who can sort-of tell the future… in weird prophecies which rhyme and at least mention one death." I told her.

She looked a bit miffed. "Well, if you say so… I still don't _get_ Divination."

Then, Carter dragged Sadie, who was laughing so hard she was clutching her stomach, into the bookstore.

"_Oh my gods!_" By now she was howling with laughter. "They use sticks to cast spells… that makes _no sense_ at all!"

"Sorry." Carter groaned. "She just won't stop laughing."

"What would you do with a _stick_? Poke people with it? Stab them in the eye?"

"Rachel once did nail Kro- I mean Grandfather in the eye with a blue plastic hairbrush." I supplied. Then I caught Hermione looking at them with a confused expression. The poor girl must've not understood what we were talking about. So I told her, "Long story. You wouldn't want to know."

She huffed and walked away.

Sadie's POV

Carter and I went to get our robes for school after meeting up with Percy and Hermione. Quite unfortunately, someone bumped into me when I was walking in the entrance.

I immediately looked up to see a blonde boy who was a bit older than me-around Carter's age, by the side of a woman who looked like his mother.

He sneered. "Apologize."

"You bumped into me first. _You_ should be the one who's apologizing." I argued.

"Who do you think you are?" Scowling, he took a step towards me. I took a step back. "Scared now, aren't we?" He taunted.

I took a deep breath and started to talk, my voice dangerously calm. "I don't know who you think I am," My eyes flared with anger, "But I'm not a weak little girl who's scared of somebody whose father spoilt them like a rich little brat. I'm backing down because I'm refraining myself from hurting you, or endangering the people around us. So if you don't want to get hurt, you better _get out of my sight_."

The boy scoffed. "As if you could scare me, you little Mudblo-"

"Draco, stop." Who I assumed to be his mother said sharply. She studied me with a glimmer of interest, and fear in her eyes. "Deal with your childish arguments at school. What will your father say of this?"

With that, she turned and walked away, her robes swishing behind her. 'Draco' glared at me one last time before he too left the scene.

"Sadie! Carter!" Leo pushed his way through the crowd. "It's time to go!"

I took a look at the store behind me. 'Draco' and his mother were completely out of sight now. "Let's go."


	4. Chapter 4

**Chapter 4: All aboard the Hogwarts Express!**

Percy's POV

We're going to school today. And that's the worst thing we've had to do for a while.

Leo and I gulped as we faced the brick wall. Funny that we've basically defeated the earth but are still afraid to run into a wall.

"I don't think to be willing to run into a brick wall was in our job description..." Leo started.

"... and also, bricks are more like Jason's thing." I finished.

"I'll go first." As it turns out, these scrawny wizards were braver than we were being right now.

Five minutes later, I closed my eyes and took a deep breath. "God/ goddess of magic brick walls… keep me safe and I'll sacrifice three-quarters of the food on my plate for you every night."

I squinted my eyes and charged.

'Boom!' I slammed into the wall and crumpled onto the ground, unconscious.

Just kidding. At least, that's what I _thought_ would happen.

In reality, I emerged on the other side. What immediately caught my eye was the red train that was currently in the station. I was speechless.

"Hey dude, you made it." Leo clapped me on the back. "Still, if you didn't make it, it would've been funny to see tomorrow's newspaper headlines: 'Percy Jackson Slams into Magical Wall and Dies from Several Head Injuries'."

The others laughed and Mrs. Weasley smiled kindly and told us to get on the train. We did so and I saw Harry and Ron out of the corner of my eye.

"... prefects' cabin." Ron seemed to say. Hermione was nodding her head.

Harry looked really disappointed but he agreed and instead joined us on the train.

We looked around, trying to find an empty compartment until at last, we found one. There was a blonde, pale girl and a boy with a round-ish face sitting inside, and it seemed that there was no one else occupying the compartment.

Leo, Carter, Sadie, Harry and I pushed open the door, walked inside, and plopped down onto the cushion-padded seats.

"Hi, Neville, Luna." Harry addressed them glumly.

Leo stared at the upside-down magazine in the girl's hands. "Your magazine is upside down."

She continued reading, ignoring Leo's statement. "_You're_ Harry Potter." She told Harry dreamily.

"I know I am."

We sat in the uncomfortable silence.

Later Ron and Hermione joined us. "Guess who's the Slytherin prefect?" Ron was scowling.

"Draco Malfoy? No way," Harry frowned at the mention of this 'Draco' person.

"Uh, blonde hair, grey eyes? Snobby and spoilt guy? That Draco?" Sadie guessed.

"How'd you know?" Hermione narrowed her eyes at Sadie.

"Relax, it's not like I'm his friend or something," Sadie scoffed. "Bumped into him while getting our school robes. Dude fled after I threatened him."

"You _threatened_ Malfoy?" Ron said incredulously, looking at Sadie with new respect.

"I did." She smirked.

"What you did wasn't even called _threatening_," an annoying voice drawled. "Now that my mother's not here, I'm going to teach you a lesson."

"Malfoy." Harry's voice took a sharp edge.

"Not cool, man. If you wanna beat somebody up, do it alone. Not with your 2 cronies to help you." Leo joked, but his hair was already starting to smoke. He hated bullies; everyone at camp knew that.

"Leo, your hair." Carter reminded him.

"Oops. Whatever." Leo waved a hand at Carter. "It'll scare him."

I cleared my throat. "Don't force me to put it out myself, Leo."

"Fine." He grumbled and patted his hair. It immediately stopped smoking.

Malfoy sneered at us. "So who's this? Some American exchange student? No doubt Dumbledore sent you here to protect Potter from his own _hallucinations._"

"Nice to meet you," I chose to ignore his words, which had been partially right, "I'm Peter Johnson."

"Leo McShizzle." Leo managed to keep a straight face. We winked at our friends and Sadie muttered something in Ancient Egyptian. Carter snorted.

"So Johnson, McShizzle," Malfoy smiled maliciously, "What's your blood status?"

"We're half-bloods." I smiled back fakely. "Not that it's any of your business."

"Be careful about who you choose to ally yourself with," He threatened. "Someday it may cost you your life, just like what happened to Potter's foolish parents."

"Back at you." Sadie shot at him.

"Don't you dare insult my parents, Malfoy." Harry trembled with rage. "You have- you have no idea-"

Carter, who had stayed silent, spoke up. "When somebody's parents sacrificed themselves to save somebody they love or possibly the world, _don't insult them_. They stopped Voldemort and if not for them, _half of the students in Hogwarts would be dead by now._"

"Very well. I will leave your group of pathetic blood traitors and Mudbloods alone," Malfoy sneered. "But be careful, Potter. Don't want anyone to find out about your little pet, do we?"

Harry and Hermione stiffened and Sadie slammed the door shut behind Malfoy. "Annoying git." She growled.

Harry exchanged a knowing glance with Hermione. Something was up, but they didn't let us know about what was wrong. I ignored the feeling that whatever Malfoy just said, there was a fairly important hidden meaning behind it.

A few hours later I came out of the toilet in my robes as the train came to a stop.

"Is this cotton?" Sadie murmured as she examined a piece of cloth from her robe.

Leo turned to me and grinned like he was about to trash the whole school within five minutes, which knowing him, was totally possible, "We're here."

I rolled my eyes. "Duh. Let's go."


	5. Author's Note

**Right, so I've decided to rewrite this with not-so-out-of-character characters, an actual plot and a prophecy. I probably won't update this very soon - I'm planning on working on my ****_other_**** story, Lost in England, before moving back to this one.**

**So yeah, slow updates + long hiatus.**

**If you followed or favorited this story, I'm genuinely sorry for not continuing this one. Once I start writing another one, I'll probably replace that one with this one, so in the meantime, feel free to take this story as your own and continue it in your own creative way. If you do, you can leave a message in the reviews telling others where to find your version of this story :)**

**Thank you for reading this and have a good day!**


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